BS ISO 7725:2020 pdf free.Rubber and rubber products – Determination of chlorine and bromine content.
BS ISO 7725 This document specifies methods for the determination of chlorine and/or bromine present in raw rubber as well as vulcanized or unvulcanized rubber compounds.The methods are applicable to natural rubbers and to the following synthetic rubbers: isoprene,styrene-butadiene, butadiene, butyl, halogenated butyl, nitrile, ethylene-propylene, chloroprene and epichlorohydrin.2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 1795, Rubber, raw natural and raw synthetic一Sampling and further preparative procedures ISO 3696, Water for analytical laboratory use一Specification and test methods  ISO 4661-2, Rubber; vulcanized一Preparation of samples and test pieces一Part 2: Chemical tests !A sample solution is obtained by combustion of a test piece either burnt in a tubular furnace with a stream of oxygen-containing gas and passed into a prepared solution or burnt in an oxygenic atmosphere in a flask or a bomb which contains a solution to absorb the combustion gas. The sample solution is then analysed by ion chromatography (method A) or potentiometric titration (method B) to
determine the content of chlorine and/or bromine in a sample. For rubber samples of very low halogen content, method A is preferable since the inflection point might not be obtained by method B.Inject the calibration solutions in increasing order of concentration and measure the conductivity of chloride ion and bromide ion peak area in each solution. Determine the correlation formula [calibration curve) by plotting the peak area as a function of concentration by means of linear regression.NOTE The problem is least when bromine is in excess. At its worst, when chlorine is in excess, the bromine concentration might appear high, to an extent of 5 % of the chloride ion content. The problem can be minimized by carrying out the titration at 60 °C and keeping the rate of addition of titrant to a minimum[2].BS ISO 7725 pdf download.